add background fetch for mod compatibility list (#651)

1 files changed, 92 insertions, 0 deletions

diff --git a/src/SMAPI.Web/BackgroundService.cs b/src/SMAPI.Web/BackgroundService.cs
new file mode 100644
index 00000000..2ccfd5f7
--- /dev/null
+++ b/src/SMAPI.Web/BackgroundService.cs
@@ -0,0 +1,92 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Hangfire;
+using Microsoft.Extensions.Hosting;
+using StardewModdingAPI.Toolkit;
+using StardewModdingAPI.Toolkit.Framework.Clients.Wiki;
+using StardewModdingAPI.Web.Framework.Caching.Wiki;
+
+namespace StardewModdingAPI.Web
+{
+    /// <summary>A hosted service which runs background data updates.</summary>
+    /// <remarks>Task methods need to be static, since otherwise Hangfire will try to serialise the entire instance.</remarks>
+    internal class BackgroundService : IHostedService, IDisposable
+    {
+        /*********
+        ** Fields
+        *********/
+        /// <summary>The background task server.</summary>
+        private static BackgroundJobServer JobServer;
+
+        /// <summary>The cache in which to store mod metadata.</summary>
+        private static IWikiCacheRepository WikiCache;
+
+
+        /*********
+        ** Public methods
+        *********/
+        /****
+        ** Hosted service
+        ****/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="wikiCache">The cache in which to store mod metadata.</param>
+        public BackgroundService(IWikiCacheRepository wikiCache)
+        {
+            BackgroundService.WikiCache = wikiCache;
+        }
+
+        /// <summary>Start the service.</summary>
+        /// <param name="cancellationToken">Tracks whether the start process has been aborted.</param>
+        public Task StartAsync(CancellationToken cancellationToken)
+        {
+            this.TryInit();
+
+            // set startup tasks
+            BackgroundJob.Enqueue(() => BackgroundService.UpdateWikiAsync());
+
+            // set recurring tasks
+            RecurringJob.AddOrUpdate(() => BackgroundService.UpdateWikiAsync(), "*/10 * * * *");
+
+            return Task.CompletedTask;
+        }
+
+        /// <summary>Triggered when the application host is performing a graceful shutdown.</summary>
+        /// <param name="cancellationToken">Tracks whether the shutdown process should no longer be graceful.</param>
+        public async Task StopAsync(CancellationToken cancellationToken)
+        {
+            if (BackgroundService.JobServer != null)
+                await BackgroundService.JobServer.WaitForShutdownAsync(cancellationToken);
+        }
+
+        /// <summary>Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.</summary>
+        public void Dispose()
+        {
+            BackgroundService.JobServer?.Dispose();
+        }
+
+        /****
+        ** Tasks
+        ****/
+        /// <summary>Update the cached wiki metadata.</summary>
+        public static async Task UpdateWikiAsync()
+        {
+            WikiModList wikiCompatList = await new ModToolkit().GetWikiCompatibilityListAsync();
+            BackgroundService.WikiCache.SaveWikiData(wikiCompatList.StableVersion, wikiCompatList.BetaVersion, wikiCompatList.Mods, out _, out _);
+        }
+
+
+        /*********
+        ** Private method
+        *********/
+        /// <summary>Initialise the background service if it's not already initialised.</summary>
+        /// <exception cref="InvalidOperationException">The background service is already initialised.</exception>
+        private void TryInit()
+        {
+            if (BackgroundService.JobServer != null)
+                throw new InvalidOperationException("The scheduler service is already started.");
+
+            BackgroundService.JobServer = new BackgroundJobServer();
+        }
+    }
+}